What is Evolution Theory in Biology

What is evolution? Is it a theory? A fact? A process?

When someone talks about evolution, they are discussing Charles Darwin's evolution theory, which states that a species can change to adapt to environmental demands. Through the process of natural selection, a species will change in order to survive, leading to changes in the species' genetic code. This theory of biological evolution is proven through fossil records and observation of changes in species over time.

Darwin's Inspiration
Charles Darwin came up with this theory when he found plants and animals in isolated regions that had changed dramatically from their genetic cousins to adapt to the environmental stresses of the particular region. This led him to the idea that all life evolved from previous forms of life, a premise that was laughed at in Darwin's time and is hotly debated even today.

Principles of Evolution Theory
The central idea of evolution theory is that all life must adapt to its environment in order to survive. If a disease comes through that wipes out 99% of a species of bird, the 1% that is immune to the disease will survive and create more birds that are naturally immune to the disease. Likewise, a species of gazelle may evolve because of predators. The slowest and weakest gazelles are eaten by predators, leaving only the strongest and fastest gazelles to reproduce. This creates a species of fast, strong gazelles that can evade predators.

It makes sense that over time, species would adapt to the demands placed upon them by their environment, sometimes becoming quite different from the original creatures. Depending on the adaptability of the creature and the environmental demands placed on each generation, the amount of evolutionary change can vary considerably.

Some of the questions related to this theory include the following:

• Just how much does natural selection affect a species of animal?
• How much change is reasonably possible?
• How long does evolutionary change take to significantly alter a species?
• Does natural selection actually cause a change in genetic coding?

All of these questions are subject to debate and investigation by the scientific community.